Hello all! Like the rest of you, this has been bothering me for YEARS. I'll describe the game to the best of my ability.
This is a PC game. You can choose to play either as a boy or a girl (I think the boy had brown hair, the girl might have had red). You were on a blue dance floor in space, and there was always a DJ in the top center of your screen who said things like "Way to boogie!" Basically, the object of each level was to light up each of the squares on the dance floor, which you did by going over them. You used the arrow keys to change the direction of your movement, but if I remember correctly, once you started you couldn't stop until you finished the level (otherwise the character would dance right off the edge of the dance floor, fall into space, and die). When you moved, your hips moved side-to-side like you were dancing. When you beat the level, you would sort of zoom up to the next dance floor. The dance floors each had a different layout. In addition, there were different obstacles as you got to the higher levels. For example, if you hit a strip of "ice" you would slide the entire length of the ice and you couldn't change direction until the end. Another one was a poison cloud that would kill you if you went through it.
Please, please, please help me figure out what this game is! I haven't played this game since 2008, and it's really making me angry that I can't find it. I would really appreciate any help you can give!